Inventors:
William E. Solano - Pittsburgh PA
James P. Docherty - Pittsburgh PA
Joseph W. Stubenbort - Pittsburgh PA
Assignee:
Salem Furnace Co. - Pittsburgh PA
International Classification:
F27D 1300
Abstract:
Bulk materials containing volatile constituents are calcined in a two-stage process comprising a first heating stage at de-volatilizing temperature but below calcining temperature during which the material is turned over and mixed to accelerate its bulk heating rate without substantially accelerating local heating rate. The first heating stage is followed by a second heating stage at calcining temperature. A rotary hearth furnace adapted for the above process is divided into outer and inner connecting annular heating zones and has rabble means for turning over and mixing the charge in the outer zone and rabble means for transporting the charge through both zones.